Various types of plungers are used to lift fluids from an oil or gas well in which the plunger acts as a piston within a well conduit and gas under pressure, either natural or artificial, lifts the plunger and fluids to the surface. Such systems are used to dewater gas wells to prevent the water from impeding the flow of the gas, are used in oil wells having a high gas-oil ratio, and are used in other wells requiring removal of troublesome well liquids. By using a piston in the well conduit, a seal is obtained between gas and fluids including liquids to permit gas expansion, either natural or artificial, to lift the fluids. That is, gas under pressure lifts the piston and fluids to the surface and the piston is cycled to the bottom of the well to again entrap fluids and remove them from the well.
The present invention is directed to an improved piston pump which will automatically retract when the pump reaches the top of the well thereby returning to the bottom of the well by gravity, and will expand when the pump reaches the bottom of the well for entrapping and removing fluids from the well by the action of gas under pressure below the pump.